docs: def count_missing(self, data, output="number"):
          """ ???
          
          Parameters
          ----------
          data    : pd.DataFrame()
              Input dataframe.
          output  : str
              Sting indicating the output of function (number or percent)
  
          Returns
          -------
          int/float
              Count of missing data (int or float)
  
          """
  
          count = self._find_missing(data,return_bool=False).sum()
  
          if output == "number":
              return count
          elif output == "percent":
              return ((count / (data.shape[0])) * 100)